Grimm Jimm, Palma David, Senan Suresh, Xue Jinyu
Holy Redeemer Hospital, Meadowbrook, Pennsylvania, USA.
London Regional Cancer Program, London, ON, Canada.
J Radiosurg SBRT. 2013;2(2):99-104.
PURPOSE/OBJECTIVE: To determine clinically relevant SBRT/stereotactic ablative radiotherapy (SABR) dose tolerance limits for RP based on statistical analysis of outcomes data.
Eighteen consecutive patients who were treated using volumetric modulated arc therapy (RapidArc) for lung tumors exceeding 80cc were assessed. Clinical outcomes have been published elsewhere, and here we present a normal tissue complication probability (NTCP) analysis. The dose volume histogram (DVH) reduction techniques of total lung V20Gy, V15Gy, V10Gy, V5Gy and mean lung dose (MLD) were each analyzed, as well as ipsilateral lung V5Gy and contralateral lung V5Gy, using the DVH Evaluator software tool. The framework of the Lyman Model was used except that each DVH reduction method was analyzed independently instead of using the power-law relationship for volume dependence. Model parameters were fitted using Maximum Likelihood.
RP was reported in 5 patients (CTC Grade 2 in 3, and Grade 3 in 2). Total lung V5Gy and contralateral lung V5Gy were the best predictors of RP (p < 0.0001 for both). For V5Gy, the 10% risk level for Grade 2-3 RP was 27.9% for total lung and 21.8% for contralateral lung. For V20Gy, the 25% risk level is 10.5% of total lung.
Analysis of RP endpoints has identified total lung V5Gy and contralateral lung V5Gy as the best predictors of RP following SBRT when delivered with RapidArc. These findings are based on limited clinical data, and longer follow-up in larger patient cohorts is required in order to determine more accurate dose tolerance limits.
基于对结果数据的统计分析，确定与放射性肺炎（RP）相关的立体定向体部放疗（SBRT）/立体定向消融放疗（SABR）的临床剂量耐受限度。
对18例连续使用容积调强弧形放疗（RapidArc）治疗80cc以上肺部肿瘤的患者进行评估。临床结果已在其他地方发表，在此我们进行正常组织并发症概率（NTCP）分析。使用DVH评估软件工具，分别分析全肺V20Gy、V15Gy、V10Gy、V5Gy和平均肺剂量（MLD）以及同侧肺V5Gy和对侧肺V5Gy的剂量体积直方图（DVH）缩减技术。除了每种DVH缩减方法独立分析而非使用体积依赖性的幂律关系外，采用莱曼模型框架。模型参数使用最大似然法拟合。
5例患者出现放射性肺炎（CTC 2级3例，3级2例）。全肺V5Gy和对侧肺V5Gy是放射性肺炎的最佳预测指标（两者p均<0.0001）。对于V5Gy，2 - 3级放射性肺炎的10%风险水平，全肺为27.9%，对侧肺为21.8%。对于V20Gy，25%风险水平为全肺的10.5%。
对放射性肺炎终点的分析已确定，在使用RapidArc进行SBRT时，全肺V5Gy和对侧肺V5Gy是放射性肺炎的最佳预测指标。这些发现基于有限的临床数据，需要在更大的患者队列中进行更长时间的随访，以确定更准确的剂量耐受限度。
